Answer:
15. 2.5 M
16. 2.5 moles
17. 0.128 M
18. 56 g
Step-by-step explanation:
15. Determination of the molarity of NaOH.
Mole of NaOH = 2.5 moles
Volume = 1 L
Molarity =?
Molarity = mole /Volume
Molarity of NaOH = 2.5 / 1
Molarity of NaOH = 2.5 M
16. Determination of the number of mole of solute.
Volume = 1 L
Molarity = 2.5 M
Mole of HCl =?
Molarity = mole /Volume
2.5 = mole of HCl /1
Mole of HCl = 2.5 moles.
17. Determination of the molarity of Na₂S
We'll begin by calculating the number of mole in 20 g of Na₂S. This can be obtained as follow:
Mass of Na₂S = 20 g
Molar mass of Na₂S = (23×2) + 32
= 46 + 32
= 78 g/mol
Mole of Na₂S =?
Molar = mass / molar mass
Mole of Na₂S = 20 / 78
Mole of Na₂S = 0.256 mole
Finally, we shall determine the molarity of Na₂S. This can be obtained as follow:
Mole of Na₂S = 0.256 mole
Volume = 2 L
Molarity of Na₂S =?
Molarity = mole /Volume
Molarity of Na₂S = 0.256 / 2
Molarity of Na₂S = 0.128 M
18. Determination of the mass of solute.
We'll begin by calculating the number of mole solute (CH₄) in the solution. This can be obtained as follow:
Volume = 1 L
Molarity of CH₄ = 3.5 M
Mole of CH₄ =?
Molarity = mole / Volume
3.5 = mole of CH₄ / 1
Mole of CH₄ = 3.5 moles
Finally, we shall determine the mass of the solute (CH₄). This can be obtained as follow:
Mole of CH₄ = 3.5 moles
Molar mass of CH₄ = 12 + (4×1)
= 12 + 4
= 16 g/mol
Mass of CH₄ =?
Mole = mass /Molar mass
3.5 = Mass of CH₄ / 16
Cross multiply
Mass of CH₄ = 3.5 × 16
Mass of CH₄ = 56 g